Synthesis, surface properties and performance of thiosulphate-substituted plasticized poly(vinyl chloride)

Plasticized poly(vinyl chloride) (PVC) was surface modified by nucleophilic substitution of the chlorine atoms of PVC by thiosulphate in aqueous media in the presence of a phase-transfer catalyst. The properties of the modified surface were evaluated by contact angle measurements, attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Migration of the plasticizer di-(2-ethylhexyl) phthalate from control as well as modified PVC was examined in hexane, in cottonseed oil and in poly(ethylene glycol)-400 (PEG-400). While the modified PVC was found to be highly migration resistant in hexane, cottonseed oil and PEG-400 extracted the plasticizer. The modified PVC was found to cause haemolysis and was cytotoxic. A possible explanation for the difference in performance of the modified material in different extraction media and its toxicity is presented from a mechanistic view of the substitution process.